1. Field
The present invention generally relates to apparatus and methods that use reflectometry.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
A time-domain (TD) reflectometer is an instrument that is designed to characterize the impulse response of an object, device, or system under test. Depending on the type of the probe waves, a TD reflectometer can be classified as an acoustic reflectometer, a radio-frequency reflectometer, an optical reflectometer, etc. Exemplary applications that rely on TD reflectometers include but are not limited to fault diagnostics for coaxial cables and optical channels, integrity tests for printed circuit boards, waveguides, and wiring systems, detection of leaks in ducts and pipelines, and medical diagnostics of bodily cavities, such as the respiratory system and the ears, nose, and throat.
For example, a representative optical TD reflectometer operates by firing an optical pulse into an optical line under test and then recording one or more reflections of this pulse from one or more defects (if any) along the length of the optical line. More specifically, the optical pulse may undergoes partial reflection and partial transmission at each defect, thereby creating reflected optical signals. These reflected optical signals may travel back to the reflectometer to be detected and correlated with the original optical pulse to determine the location and strength of each defect.